1. Field of the Invention
The present invention relates to a moving image decoding apparatus which is equipped in a broadcast receiving terminal that receives, e.g., a digital broadcast signal for a mobile object using a ground wave, and a digital broadcast signal for a mobile object using a satellite.
2. Description of the Related Art
Modulation and demodulation techniques of video media have been increasingly progressing in recent years. This results from an increase in information volume due to higher qualities of moving image and audio data, and a higher demand for transmission of image information via networks due to development of wired or wireless networks.
Especially, since moving image data has a large volume, the moving image modulation and demodulation techniques are demanded to have high compression efficiency, high quality after demodulation, high transmission efficiency, and the like. As moving image modulation and demodulation techniques that meet such demands, a technique called ITU-T recommendation H.264/AVC (advanced video coding) (to be simply referred to as H.264 hereinafter) is known. The moving image modulation and demodulation techniques are disclosed in, e.g., IEEE Transactions on Circuits and Systems for Video Technology, Vol. 13, No. 7, July 2003, Overview of the H.264/AVC Video Coding Standard, Thomas Wiegand.
When H.264 AVC is applied to a ground wave digital broadcast system for a mobile object or a satellite mobile broadcast system, H.264 stream data is multiplexed in MPEG-2 systems together with information such as data broadcast data, and the like, and the multiplexed stream data is transmitted toward respective receiving terminals. However, when the receiving terminal is a mobile terminal such as a portable terminal, in-vehicle terminal, or the like, the receiving terminal is on the move. For this reason, reception of stream data in a stable radio wave environment is not always possible. Especially, in an environment in which a receiving terminal is in the shade of buildings and the like, errors mix in stream data at a high frequency of occurrence. Therefore, a moving image decoding apparatus equipped in a mobile terminal must have an error resilient function, and various examinations have been made (for example, Hiroshi Mori, Hirokazu Kawakatsu, & Masakazu Suzuki, “One examination of reproduction image under error environment in H.264”, Technical Report of IEICE, IE2004-18, May, 2004”).
However, most of examinations of error resilience techniques that have been made so far are intended for a concealment scheme of missing macroblocks (MB), and deterioration of image quality due to interpretation errors of a syntax that represents setting rules of an encoded data sequence and the like have not been sufficiently discussed.